1. Field of the Invention
The present invention relates to an inkjet printer, and more particularly, to a carrier locking apparatus for an inkjet printer, to lock a carrier, in which at least one ink cartridge is mounted, in a home position, to withstand external impact or vibration.
2. Description of the Related Art
In general, an inkjet printer is a printer in which an image is formed on a recording medium by jetting ink droplets onto the recording medium from at least one ink cartridge mounted in a carrier that reciprocates perpendicularly to the transfer direction of the recording medium. In particular, in a color inkjet printer, a mono-cartridge containing a black ink, and color cartridges containing various color inks, for example, cyan, magenta, and yellow, are mounted in a carrier, and a color image can be printed by combining these color inks.
FIG. 1 is a perspective view illustrating a conventional carrier of an inkjet printer, a carrier moving apparatus, and a carrier parking apparatus, and FIG. 2 is an enlarged perspective view illustrating the carrier parking apparatus of FIG. 1.
Referring to FIGS. 1 and 2, an inkjet printer has a carrier 10 for reciprocating ink cartridges 12 mounted therein. The carrier 10 is moved by a carrier belt 40, and guided by a guide shaft 30. The carrier belt 40 is wound around a driving pulley 42 and a driven pulley 46, and a portion of the carrier belt 40 is held by a belt holder (not shown) provided at the rear side of the carrier 10. The driving pulley 42 is connected to and driven by a rotation shaft of a driving motor 44 to circulate the carrier belt 40. The circulation direction of the carrier belt 40 is changed according to the rotation direction of the driving pulley 42. When the carrier belt 40 circulates, the carrier 10 moves linearly along the guide shaft 30. Reference numeral 48 denotes a spring that applies a predetermined tensional force to the carrier belt 40.
When the printer is not in operation, the carrier 10 is parked at a home position provided at one end portion of the inkjet printer. A parking apparatus 50 is provided at the home position, and caps 55 are installed at the parking apparatus 50 to cover respective head chips 14 (FIG. 3A) provided at the lower surfaces of the ink cartridges 12. Each head chip 14 has a plurality of nozzles for jetting ink, and when the carrier 10 is parked at the home position, the caps 55 cover the respective head chips 14. Once the cap 55 covers the head chip 14, ink leakage from the nozzles of the head chip 14 is prevented since the internal pressure of the cap 55 is regulated to be the same as or higher than the internal pressure of the ink cartridge 12. Additionally, the cap 55 seals the head chip 14 from external air to prevent ink from clotting due to the evaporation of a volatile constituent of ink.
The parking apparatus 50 has an external frame 51 installed at a main frame 20 of the printer, and an internal frame 54 joined to the external frame 51 to move up and down along a predetermined path. Wipers 56 are installed at upper portions of the internal frame 54 to clean the respective surfaces of the head chips 14. Guide grooves 53 serving as the predetermined path are located on the external frame 51, and guide pins 57, installed at the internal frame 54, are inserted into the guide grooves 53. In addition, a parking lever 58 and an un-parking lever 59 are provided at opposing ends of the internal frame 54.
The operation of the conventional parking apparatus having the above-described structure is now described with reference to FIGS. 3A and 3B.
Referring to FIG. 3A, when the printer is operating, the carrier 10 is out of the home position, and the internal frame 54 of the parking apparatus 50 is maintained in a lowered state due to an elastic force of a spring 60. Additionally, the guide pins 57 of the internal frame 54 are positioned at lower end portions of the guide grooves 53 of the external frame 51.
When a printing job is completed, the carrier 10 moves in the direction of arrow R and pushes the parking lever 58. Accordingly, the guide pins 57 move upward along the paths of the respective guide grooves 53, and the internal frame 54 and the caps 55 move upward simultaneously. As shown in FIG. 3B, when the carrier 10 reaches the home position, the caps 55 are raised completely, and cover the respective head chips 14 of the ink cartridges 12. Further, the guide pins 57 of the internal frame 54 are positioned at upper end portions of the respective guide grooves 53 of the external frame 51.
When a printing operation is requested when the carrier 10 is parked at the home position, the carrier belt 40 is circulated by the operation of the driving motor 44, and the carrier 10 moves in the direction of arrow F along the guide shaft 30. Accordingly, the internal frame 54 is moved downward by the elastic force of the spring 60, the guide pins 57 move downward along the paths of the respective guide grooves 53, and the caps 55 move downward and separate from the head chips 14. The surfaces of the head chips 14 are cleaned by the wipers 56 when the guide pins 57 are positioned at middle portions of the guide grooves 53. Thereafter, as shown in FIG. 3A, when the carrier 10 is completely out of the home position while pushing the un-parking lever 59, the internal frame 54 is completely lowered due to the elastic force of the spring 60. Further, the guide pins 57 of the internal frame 54 are positioned at the lower end portion of the respective guide grooves 53 of the external frame 51.
In the conventional parking apparatus 50 described above, however, when an external impact or vibration is applied to the carrier 10, the carrier 10 may be easily separated from the parking apparatus 50. Further, the head chips 14 may separate from the respective caps 55, and accordingly ink may leak from the nozzles of the head chips 14. The leaked ink may cause the transfer path of a recording medium to be contaminated, and reduce the quality of printing. In addition leaked ink reduces a useful life of the ink cartridge 12. Further, when the head chips 14 are exposed, the head chips 14 may be contaminated by dust or the like, and ink may clot in the nozzles due to the evaporation of the volatile constituent of ink and block the nozzles. Further still, if the nozzles are blocked, ink will not jet through the nozzles properly, and the quality of printing deteriorates further. Also, when the carrier 10 is separated from the home position and allowed to rattle freely, the carrier 10 and the head chips 14 may be easily damaged.